Latching mechanism for access door



Sept. 26, 1961 R. GoDsHALK ETAL LATCHING MECHANISM FOR ACCESS DOOR FiledApril l5, 1958 2 Sheets-Sheet 1 IN V EN TORS Russell L. Godshalk R beriE. Lowe ATTORNEY SePt- 26, 1961 R. L GoDsHALK ETAL 3,001,488

LATCHING MECHANISM FOR ACCESS DOOR Filed April l5, 1958 2 Sheets-Sheet 2FIG. 4

56 1 f 72k- Issm :i 72B/` /L f|1 M 44 I INVENToRs Russell L. Godshalk BYRoberr E. Lowe MAM' ATTORNEY LATCG MlECSM EUR ACCESS DOOR Russell L.Godshalk, Akron, hio, and Robert E. Lowe,

Westport, Conn., assignors to The Babcock 8L Wilcox glompany, New York,NY., a corporation of New ersey Filed Apr. 15, 1958, Ser. No. 728,683 6Claims. (Cl. 11d- 176) This invention relates to an access door assemblyparticularly adapted for an opening formed in a boundary wall of afurnace or chamber within which high temperature gases at a pressureconsiderably above atmospheric pressure are generated or flowing.

When a wall opening is provided through which access may be had to afurnace or chamber of the character described lfor `cleaning orobservation, it is essential that the opening be iitted with -a doorassembly so constructed and arranged as to safeguard the operator fromblasting by hot gases when the `door is opened. With the usual doorconstruction for a furnace under pressure, high pressure aspirating airis introduced into the access opening to counter the discharge of hotgases, with the aspirating air supply control valve interlocked with thedoor latching mechanism to prevent opening of the door until the aircontrol valve is in operating position and with the door completely freeto move from its closed to fully open position once the latchingmechanism is released. Experience has proven that a definite hazardexists with this door construction under a condition Where the aircontrol valve is turned on preparatory to unlatching the door andaspirating air flow is either inadequate or non-existent for somereason, such as pluggage of the valve, or fails prior to release of thedoor. Frequently the operator is unaware of the air flow deficiency orfailure until the door is opened. Since the latching mechanism on thistype of door has to be wholly released before the door can be opened, anincautious operator rapidly swing the door open would be blasted by thehot gases in the absence of mechanical constraint of the door in itsoutward movement from closed position. Even a cautious operator would besubject to this danger upon the sudden opening of a sticky door afterthe application of force.

The main object of the present invention is to provide an access doorassembly of the character described which is simple to construct andoperate, and has components so interlocked as to insure positiveprotection at all times to the operating personnel despite possiblecarelessness on their part or sticking of the door to its seat. Inaccordance with the present invention, the outer end of an openingformed in a boundary wall of a chamber conning high temperature gasesunder superatmospheric pressure is closed by a door pivotally connectedto the wall. Provision is made for directing high pressure aspiratinggaseous fluid into the opening in the direction of the chamber tocounter the discharge of hot gases when the door is opened for lancingor observation purposes; and for preventing outward movement of the dooruntil the control for high pressure aspirating iluid supply is set inflow position. The door latching mechanism comprises a latch normallyinterlocked with the door and pivotally connected to the wall formovement into and out of locking relation with the door; and latchadjusting means associated with the latch and cooperating therewith tolock and unlock the door. Provision is made for effecting outwardmovement of the door, while preventing pivotal movement of the latch andmaintaining the latch in interlocking relation with the door until thedoor is at least partially opened. This arrangement provides positiveconstraint of the door in its outward ddlASS Patented Sept. 26, 1961movement from closed position until the operator is assured that theaspirating air supply system is functioning properly and to the extentthat the operator will be apprised of and protected `from gas blastingin the event that the aspirating air supply is deficient ornon-existent.

rThe various features of novelty which characterize our invention arepointed out with particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,its operating advantages and specific objects attained by its use,reference should be had to the accompanying drawings and descriptivematter in which we have illustrated and described a specific embodimentof our invention.

Of the drawings:

FIG. 1 is a front elevation of an access door assembly constructed inaccordance with our invention;

FIG. 2 is a plan section taken along the line 2-2 of FIG. l;

FIG. 3 is a sectional elevation taken along the line 3-3 of FIG. l;

FIG. 4 is an enlarged fragmentary plan section showing the door latchingmechanism;

FIG. 5 is a vertical section taken along the line 5-5 of FIG. 4; and

FIG. 6 is a vertical section taken along the line 6--6 of FIG. 4.

In the embodiment of the invention shown in the drawings the doorassembly is associated with a wall 10 including vertically extendingfluid cooled tubes l2, having an opening 14 therein, and providing aboundary for a chamber or furnace 16 within which high temperaturegenerated or flowing. The opening 14 is formed in known manner bydisplacing intermediate portions of adjoining pairs of some of the tubes12 laterally or outgases at a pressure well above atmospheric pressureare wardly. The wall lil includes inner metal casing 18 suitably securedto the tubes l2, insulation 20 and outer metal casing 22; and cooperateswith other walls of similar construction to provide a sealed chamberpermitting operation at high positive gas pressures.

An inner frame 24 is symmetrically arranged in the opening 14 and formsa passage 26 of circular crosssection opening to the chamber 16 at itsinner end. The inner frame 24 comprises a cylindrical sleeve section 28and a frusto-conical section 3d disposed coaxially of the sleeve 28 andhaving an apex angle of about 70. The sleeve 28 is secured by welding toan outer frame 32 disposed adjacent the perimeter of the opening 14 andsurrounding most of the inner frame 24; .is beveled at its inner end;and is formed with an annular lip 28A at its outer end extendingradially inward. The frusto-conical section 30 has its inner enddisposed within and in sealing relation with the lip 28A, divergesoutwardly from the sleeve 28, and is secured at its outer end by weldingto the outer frame 32.

In order to prevent escape of hot gases when the access opening 14 isuncovered for lancing or observation of the chamber 16, provision ismade for directing jets of high pressure, high velocity gaseous fluid,such as air or steam, into the passage 26 in the direction of thechamber 16. For this purpose, the outer frame 32 cooperates with theinner frame 24 to define an air manifold 34. Circumferentially spaced,angularly directed holes 36 are drilled in the lip 28A for the dischargeof jets of air into the passage 26 in converging relation with the axisthereof and preferably at an angle of about 6 relative to the axis.Compressed air or other gaseous fluid relatively high pressure isdelivered to the manifold 34 through pipes 38, 39 and 40, the supply offluid being controlled by a three-way valve 42. The pipes 39 and 40 areconnected by a T-titting 4.1 into which is threaded a cap screw 43 foradjustment of the aspirating air supply to the passage 26.

The outer end of the outer vframe 32 is formed with a rectangularlateral extension or flange 44 suitably secured to and overlapping theouter casing 22. A circular door 46 formed at one side with a pair ofvertically spaced laterally extending a1ms 43 is pivotally connected toapair of vertically spaced and aligned lugs Sil on the outer face of theilange 44 by eccentric pivot pins S2 engaging the arms 48 and the lugs50. Thus the door is hinged for movement about a Vertical axis parallelto the wall 10. T-he opposite side of the door is formed with anextension 54 projecting outwardly and then laterally yand having aU-shaped groove 56 formed in the outer end thereof. A groove 58 isformed in the inner face of the door 46 and illed with asbestos or othersuitable packing material 66) to provide a gas-tight seal between thedoor and the ange 44 when the door is closed. The pivot pins 52 areeccentrically formed so that they can be adjusted to obtain maxim-umsealing contact between the llange 44 and the packing 60.

In accordance with the invention and as clearly illustrated in FIGS.3-6, the door latching mechanism comprises latch guide means whichincludes a pair of vertically spaced and aligned lugs 62 secured to theflange 44 and each formed with an outwardly and horizontally projectingbeveled stop 65. An externally threaded latch or eye bolt 66 of adiameter less than the spacing between the lugs 62 is interlocked withthe door 46 in the groove 56 thereof and is pivotally connected betweenthe lugs 62 by a pin 68 for movement into and out of locking relationwith the door about a vertical axis substantially parallel to the walll0. The outer end of the door extension 54 is disposed opposite theouter ends of the stops 64 in outwardly spaced relation thereto when thedoor is in its closed position. A hand knob 76 inclurlin-g an internallythreaded tubular sleeve 72\ is threadably secured to the latch 66 andcooperates therewith to lock and unlock the door 46. The sleeve 72includes an intermediate portion 72A of reduced diameter adapted tointerlock with the door 46 in the groove 56 thereof; an outer portion'72B of an outside diameter greater than the distance between the legsof the groove 56 and arranged to engage the outer face of the dooropposite the groove 56 when the door is in its closed position; and aninner portion 72C of an outside diameter greater than the spacingbetween either the legs of the gnoove 56 or the stops 64, inwardly andhorizontally spaced yfrom the inner `face of the door opposite thegroove 56 when the door is closed, and disposed alongside the beveledportion of the stops 64 in interlocking relation therewith when the dooris in its closed position. The inner portion 72C of the sleeve 72cooperates with the stops. 64 (to prevent pivotal movement of the latch66 out of locking relation with the door and to maintain the latch 66 inlocking relation with the door until the door is at least partiallyopened.

Movement of valve 42 is manually eiected by a pivotally mounted wrench74 disposed outwardly of and interlocked with the knob 70 to preventopening of the door 46 until after the wrench 74 is rotated 90clock-wise. After the wrench 74 is so rotated and assuming that theaspirating air supply system is functioning properly, air dischargesinto the passage 26 by way of the pipes 38, 39 and 40 at a pressuresuliicient to at least neutralize the pressure of the gases in thechamber i6, thereby preventing the discharge of hot gases through thepassage Z6 and permitting lancing or other operations with safety whenthe door is opened.

When the door is fully closed, as shown in the drawings, the valve 42 isin position to allow low-pressure cooling air to ow from a pipe 76 tothe passage 26 by way of the pipes 39, 49 and the `door 46 is sealedagainst the flange 44 throughout the perimeter of the packing 60 throughthe force of the sleeve portion 72 of the knob 70 engaging the latch 66and bearing against the outer face of the lateral extension 54 of thedoor. When the door is to be opened, the wrench 74 is rotated to permitiow of high pressure air into the passage 26 and the knob 70 is turnedcounterclockwise to el'I'ect outward movement of the sleeve 72. As theknob is turned counter-clockwise, the outer portion 72B of the sleeve 72`disengages from the outer face of the lateral extension 54 of the door;then the inner portion 72C of the sleeve 72 engages the inner face ofthe lateral extension 54 to effect cutwand movement of the door from itsclosed position; and then the inner portion 72C of the sleeve movesbeyond the stops 64, thereby permitting pivotal movement of the latch 66out of the door groove 56. Once the latch 66 is pivotally moved out oflocking relation with the door, the Kdoor is completely free to swingoutwardly. The lateral extension 54 is provided with `an upright handle78 to facilitate movement of the door. Thus the inner portion 72C of thesleeve 72 and the stops 64 cooperate to prevent pivotal movement of thelatch 66 and to maintain the latch 66 in interlocking relation with thedoor until the inner portion 72C of the sleeve moves beyond the stops64, while the door is positively constrained in its outward movementfrom the ilange 44 until the latch is pivotally moved out of lockingrelation therewith. In the event that the aspirating air supply to thepassage 26 is deficient or non-existent for some reason, such aspluggage of the valve 42 or pluggage of the holes 36 With ash or otherforeign matter, the operator will become aware of this fact by thedischarge of gases as soon as the door moves outwardly from the flange44.

The positive constraint of the door in its initial movement from theilange 44 and the protection afforded by the door when ythe unsafecondition becomes apparent, safeguard the operator from injury andpermit immediate closing of the door to correct the condition.

While in accordance with the provisions of the statutes we haveillustrated and ldescribed herein the best form of the invention nowknown to us, those skilled in the art will understand that changes maybe made in the form of the apparatus disclosed Without departing fromthe spirit of the invention covered by our claims, and that certain'features of our invention may sometimes be used to advantage without acorresponding use of other features.

What is claimed is:

l. In combination with a wall having an opening therein and providing aboundary for a chamber conning high temperature gases undersuperatmospheric pressure, a door pivotally connected to said wall andnormally closing the outer end of said opening, means for introducing agaseous fluid under pressure into said opening in the direction of saidchamber, and door latching means comprising latch guide means includingya stop secured to said wall, a latch normally interlocked with saiddoor and pivotally connected to said latch guide means for movement intoand out or locking relation with said door, and latch adjusting meansassociated with said latch and cooperating therewith to lock and unlocksaid door, said latch adjusting means coacting with said latch to eiectoutward movement of said door, while cooperating with said stop of saidlatch guide means to prevent pivotal movement of said latch until thedoor is at least partially opened and maintain said latch ininterlocking relation with door until the door is at least partiallyopened.

2. In combination with a wall providing a boundary for a chamberconfining high temperature gases under superatmospheric pressure, meansincluding a door frame in said wall `forming a passage extending throughsaid wall and opening at its inner end to said chamber, a door pivotallyconnected at one side to said iframe and normally closing the outer endof said passage, means for introducing a gaseous lluid under pressureinto said passage in the direction of said chamber, and door latchingmeans comprising latch guide means including a stop secured to saidframe, a latch normally interlocked with said door at the opposite sidethereof and pivotally connected to said latch guide means for movementinto and out of locking relation with said door, and latch adjustingmeans `associated with said latch and cooperating therewith to lock andunlock said door, said latch adjusting means coacting with said latch toeiect outward movement of said door, while cooperating with said stop ofsaid latch guide means to prevent pivotal movement of said latch untilthe door is at least partially opened and maintain said latch ininterlocking relation with said door until the door is at leastpartially opened.

3. In combination with a wall having an opening therein and providing aboundary for a chamber coniining high temperature gases undersuperatmospheric pressure, a door pivotally connected at one side tosaid wall and normally closing the outer end ot said opening, meansincluding a valve controlled conduit for introducing a gaseous fluidunder pressure into said opening inthe direction of said chamber, meansfor preventing opening of said door until the valve of said conduit isopened, and door latching means comprising latch guide means including astop secured to said wall, a latch normally interlocked with said doorat the opposite side thereof and pivotally connected to said latch guidemeans for movement into and out of locking relation with said door, andlatch adjusting means associated with said latch and cooperatingtherewith to lock and unlock said door, said latch adjusting meanscoacting with said latch to effect outward movement of said door, whilecooperating with Said stop of said latch guide means to prevent pivotalmovement of said latch until the door is at least partially opened andmaintain said latch in interlocking relation with said door until thedoor is at least partially opened.

4. In combination with a wall providing a boundary for a chamberconfining high temperature gases under superatmospheric pressure, meansincluding a door frame in said wall forming a passage extending throughsaid Wall and opening at its inner end to said chamber, a door pivotallyconnected at one side to said frame and normally closing the outer endof said passage, means including a valve controlled conduit -forintroducing a gaseous uid under pressure into said passage in thedirection of said chamber, means for preventing opening of said dooruntil the valve of said conduit is opened, and door latching meanscomprising latch guide means secured to said frame and including a lugformed with an outwardly projecting stop, a latch normally interlockedwith said door at the opposite side thereof and pivotally connected tosaid latch guide means for movement into and out of locking relationwith said door, and latch adjusting means including a sleeve normallyinterlocked with said door and threadably engaging said latch andcooperating therewith to lock and unlock said door, said sleeve having aportion normally engaging the outer face of said door when the door isin its closed position and another portion arranged to engage the innerface of said door and effect outward movement of the door as the sleeveis disengaged from said latch, said other portion of said sleeve beingnormally interlocked with said stop and cooperating therewith to preventpivotal movement of said latch out of locking relation with said dooruntil the door is at least partially opened and to maintain said latchin locking relation with said door until the door is lat least partiallyopened.

5. ln combination with a wall providing a boundary for a chamber conninghigh temperature gases under superatmospheric pressure, means includinga door frame in said wall forming a passage extending through said walland opening at its inner end to said chamber, a door pivotally connectedat one side to said trame for movement about an axis substantiallyparallel to said wall and normally closing the outer end of saidpassage, said door having a groove at the opposite side thereof, meansincluding `a valve controlled conduit for introducing air into saidpassage inthe direction of said chamber at a pressure sucient to atleast neutralize the chamber pressure when the door is to be opened,means for preventing opening of said door until the valve of saidconduit is opened, and door latching means comprising latch guide meanssecured to said frame and including a pair of lugs each formed with anoutwardly projecting stop, a latch normally interlocked with said doorin the groove thereof and pivotally connected to said latch guide meansfor movement into and out of locking relation with said door about anaxis substantially parallel to said Wall, and latch adjusting meansincluding a sleeve normally interlocked lwith said door in the groovethereof and threadably engaging said latch and cooperating therewith tolock :and unlock said door, said sleeve having a portion normallyengaging the outer face of said door when the door is in its closedposition and another portion arranged to engage the inner face of saiddoor and effect outward movement of the door as the sleeve is disengagedfrom said latch, said other portion of said sleeve being normallyinterlocked with said stops and cooperating therewith to prevent pivotalmovement of said latch out of locking relation with said door until thedoor is at least partially opened and to maintain said latch in lockingrelation with said door until the door is at least partially opened.

6. In combination with a Wall providing a boundary for a chamberconfining high temperature gases under superatmospheric pressure, meansincluding a door frame iu said wall forming a passage extending throughsaid wall and opening at its inner end to said chamber, a door pivotallyconnected at one side to said frame for movement about a vertical axissubstantially parallel to said wall and normally closing the outer endof said passage, said door being formed with an extension at theopposite side thereof having a groove, means including a valvecontrolled conduit for introducing lair into said passage in thedirection of said chamber at a pressure sufficient to at leastneutralize the chamber pressure when the door is to be opened, means forpreventing opening of said door until the valve of said conduit isopened, and door latching means comprising latch guide means secured tosaid frame and including a pair of lugs each formed with an outwardlyprojecting stop, a latch normally interlocked with said door in thegroove thereof and pivotally connected to said latch guide means formovement into and out of locking relation with said door about avertical axis substantially parallel to said wall, and latch adjustingmeans including a sleeve normally interlocked with said door in thegroove thereof `and threadably engaging said latch and cooperatingtherewith to lock and unlock said door, said sleeve having a portionnormally engaging the outer face of said door when the door is in itsclosed position and another portion arranged to engage the inner face ofsaid door and effect outward movement of the door as the sleeve isdisengaged fromy said latch, said other portion of said sleeve beingnormally interlocked with said stops and cooperating therewith toprevent pivotal movement of said latch out of locking relation with saiddoor until the door is at least partially opened and to maintain saidlatch in locking relation with said door until the door is at leastpartially opened.

References Cited in the le of this patent UNITED STATES PATENTS 781,371Sherman Jan. 31, 1905 1,583,396 Demuth May 4, 1926 1,769,979 WhittamJuly 8, 1930 2,393,078 Wager Jan. 15, 1946 2,758,554 Ohman Aug. 14, 1956FOREIGN PATENTS 652,009 Germany Oct. 23, 1937 6,1577 Great Britain 1889

